The original Plymouth Duster is a semi-fastback two-door version of the compact-sized Plymouth Valiant automobile that was marketed by Chrysler in the U.S. from 1970 to 1976 model years.

The Plymouth Duster introduced in late-1969 for the 1970 model year was all Valiant from the cowl forward, but the rest of the car's sheet metal, save door skins, was completely different. The design incorporated a semi-fastback roof and a special rearvalance with twin horizontal taillights, unusual for having no bezels. The door glass was operated by a new regulator mechanism, required to fit the much more radical tumble home, and the windshield was more steeply raked. For 1970 only, a small Valiant badge went on the front fenders just above the Duster badge. The1970 Duster was available in two models; the standard Duster and a performance-oriented Duster 340.